A fuel filter of an internal combustion engine has a filter housing in which water separated from the fuel may collect within the filter so as to permit collection of the largest possible quantity of separated water in the smallest possible overall volume. This fuel filter has a liquid line which leads out of an area of the filter housing that is exposed to fuel and in which separated water can settle out due to gravity into a water collecting chamber situated outside the filter housing. There is also an upper area of the water collecting chamber which is connected by a connecting line mounted there to a fuel delivery line of the internal combustion engine.